KR102138903B1 - Thickener for aqueous paint and aqueous paint composition containing the same - Google Patents

Abstract

The present invention relates to an aqueous paint composition comprising an associative cellulose ether substituted with a hydrophobic group and an aqueous paint composition comprising the same, according to the present invention, an associative thickener comprising a cellulose ether having a hydrophobic group in a specific degree of substitution By providing the can improve the thickening efficiency and storage stability of the water-based paint composition comprising the same, it is possible to improve the overall properties of the paint, such as workability, sag resistance and color expression.

Description

Thickener for aqueous paint and aqueous paint composition containing the same}

The present invention relates to a thickener for water-based paints comprising associative cellulose ether substituted with a hydrophobic group and an aqueous paint composition comprising the same.

Building materials for finishing, such as water-based paint, have been widely used as building finishing materials for a long time due to the protection of concrete materials, beautiful appearance, convenience in construction, and convenience in maintenance.

Water-based paints are classified into 100% acrylic emulsions, styrene-acrylic emulsions, and vinyl emulsions, depending on the type of emulsion, and the specific gravity of use increases more than oil-based paints due to market demand for eco-friendly building materials, economics, and ease of construction. Trend.

In addition, water-soluble paints are classified into external and internal paints according to their use. Previously, water-based paints have been used as exterior and interior wall paints for apartments, but the use of water-based paints has been steadily strengthened as environmental regulations on environmentally friendly materials, continuous volatile organic compounds (VOC), and environmental air management protection laws have been strengthened. Is increasing.

The elements constituting the water-based paint include resins, pigments, solvents, etc., but this alone is difficult to sufficiently satisfy many of the performances required for paints, and in some cases, it is impossible to solve them with resins or pigments alone. In this case, the physical properties of the paint can be improved by using additives, and the amount of the additive is small, but it is a very important component in the paint.

Particularly, when the shear rate is large as in the case of painting, the paint has a low apparent viscosity and is easy to apply. On the other hand, after the coating with the external force removed, the viscosity is restored and the paint is coated with an appropriate film thickness, and thixotrophy, which is an opposite property, should not flow. Although required, a small amount of thickener is used as the additive to satisfy these properties. The thickener forms a mesh-like structure with resins and pigments in the paint to give a high viscosity, but the mesh-like structure is easily destroyed by the high shearing force during painting, and thus the viscosity of the paint is lowered, thereby facilitating painting. On the other hand, if the force applied from the outside is removed, the broken net structure is restored and the viscosity rises again, so the paint after painting does not flow.

The thickener is used as an additive for water-based paint for the purpose of improving layer separation prevention, workability, thickening, leveling, and water retention properties of paint in addition to thixotropy, and a typical example of the thickener is cellulose ether.

In general, cellulose ethers for aqueous paint thickeners include hydroxyethyl cellulose (HEC), hydrophobic group substituted hydroxyethyl cellulose (HMHEC), and hydroxypropylmethyl cellulose (Hydroxypropyl cellulose), depending on the substituent. Methyl Cellulose (HPMC) is mainly used.

In particular, the hydroxypropyl methyl cellulose has the advantage of having a high viscosity, so that it can obtain a high paint viscosity even when used in a small amount, but it has a disadvantage in that its coloring power is poor and color appearance is poor even when the same pigment is added and the appearance is poor due to undissolved particles. There is this.

On the other hand, hydroxyethyl cellulose has the advantage of excellent color expression and less foam formation, but has a disadvantage of poor workability and poor thickening efficiency due to severe paint spatter during roller or brushing.

Hydroxyethyl cellulose (HMHEC) substituted with hydrophobic groups developed to improve these problems can improve workability during roller and brushing operations of aqueous paints, but has a disadvantage of poor thickening efficiency and storage stability.

Patent document 1 (Japanese Patent Application Publication No. 2012-0099327) discloses an associative thickener comprising cellulose ether. According to this method, it is possible to improve the overall properties of paint storage stability, workability, etc., but in order to realize associative properties, cellulose acetate in the thickener and a hydrophobic component, vinyl acetate-based emulsion and acrylic emulsion are included as essential components. Therefore, the cellulose ether content in the thickener is reduced compared to the existing cellulose ether thickener, thereby limiting the physical properties of the paint due to the thickener.

Therefore, the construction finishing market is demanding the development of a new cellulose ether thickener that can satisfy both workability and various paint properties.

KR 2012-0099327 A

The problem to be solved by the present invention is to provide a thickener for water-based paints capable of improving thickening efficiency and storage stability while maintaining workability.

Another problem to be solved by the present invention is to provide a water-based paint containing the thickener for the water-based paint.

In order to solve the above problems, the present invention comprises a cellulose ether substituted with a hydrophobic group, the hydrophobic group is a hydrocarbon group having 4 to 20 carbon atoms (C ₄ ~ C ₂₀ ), the degree of substitution of the hydrophobicity is 0.5 to 1.0% by weight It provides a thickener for water-based paint.

Preferably, at least one hydrogen of the hydrophobic group may be substituted with a halogen group, and the halogen group may be at least one selected from fluorine, chlorine, bromine and iodine.

The cellulose ether is preferably at least one selected from the group consisting of alkylcellulose, hydroxyalkylcellulose and hydroxyalkylalkylcellulose, more preferably the cellulose ether may be hydroxyethyl cellulose, even more preferably the cellulose The ether may be hydroxyethyl cellulose having a hydroxy ethyl group substitution degree (MS) of 0.8 to 4.5.

The viscosity of the cellulose ether is preferably 100 to 20,000 cps based on a 1% by weight aqueous solution measured at 25°C and 6 rpm with a Brookfield viscometer.

In addition, the present invention provides an aqueous paint composition comprising the thickener for water-based paint, and the content of the thickener is preferably 0.1 to 1.0% by weight based on the total weight of the water-based paint composition.

According to the present invention, by providing an associative thickener comprising a cellulose ether having a hydrophobic group in a specific substitution degree range, it is possible to improve the thickening efficiency and storage stability of the water-based paint composition containing the same.

In addition, by using the thickener, it is possible to improve overall paint properties such as workability, sag resistance, and color expression.

The present invention includes a cellulose ether substituted with a hydrophobic group, the hydrophobic group is a hydrocarbon group having 4 to 20 carbon atoms (C ₄ to C ₂₀ ), and a thickener for water-based paint having a substitution degree of 0.5 to 1.0% by weight of the hydrophobic group and the same It relates to an aqueous paint composition comprising.

The cellulose ether thickener of the present invention is an associative thickener having a hydrophobic group in a molecule, wherein the hydrophobic group substituted by the associative thickener in this specification interacts with the emulsion in the aqueous paint composition to achieve high shear rate roller work. It refers to the effect of improving the paint spatter and workability during painting by increasing the viscosity at the time.

As the hydrophobic group, a hydrocarbon group having 4 to 20 carbon atoms (C ₄ to C ₂₀ ) is used, and when the number of carbon atoms is less than 4, there is little associative property with latex particles, and thus there is no improvement effect of workability. Workability is poor and paint viscosity can be excessively high.

The degree of substitution of the hydrophobic group substituted with the cellulose ether is 0.5 to 1.0% by weight, where the degree of substitution means the average weight percent of the hydrophobic groups bound per cellulose unit of the cellulose ether substituted with a hydrophobic group. When the degree of substitution of the hydrophobic group is less than 0.5% by weight, there is little associative effect with the emulsion particles, so the effect of improving workability is negligible. On the other hand, when the degree of substitution of the hydrophobic group exceeds 1% by weight, production efficiency decreases and paint viscosity is caused by excessive association ability. Is not produced because it may be excessively high.

One or more hydrogens of the hydrophobic group may be substituted with a halogen group, and one or more selected from fluorine, chlorine, bromine and iodine is preferably used as the halogen group, and in particular, a cetyl bromide group substituted with bromine as a hydrophobic group (cetyl When bromide is used, it is more preferable because there are few undissolved particles in the product and the most suitable properties in terms of workability and thixotropy.

Meanwhile, the cellulose ether used in the present invention is preferably one selected from the group consisting of alkylcellulose, hydroxyalkylcellulose and hydroxyalkylalkylcellulose, more preferably coloring power, appearance state of paint and pigment dispersibility Excellent hydroxyethyl cellulose is used. The degree of substitution (MS) of the hydroxyethyl group of the hydroxyethyl cellulose is preferably 0.8 to 4.5, where the degree of substitution (MS) is the average of the hydroxyethyl groups bound per unit of cellulose of the hydroxyethyl cellulose. It means the number of moles, and if the substitution degree of the hydroxyethyl group is less than 0.8, solubility in water may be deteriorated, whereas when it exceeds 4.5, production efficiency is lowered and the product surface is too sticky, so product production and use may be difficult. .

In addition, the cellulose ether preferably has a viscosity of 100 to 20,000 cps based on a 1% by weight aqueous solution measured at 25° C. and 6 rpm with a Brookfield viscometer, and more preferably has a viscosity of 8,000 to 13,000 cps. When the viscosity of the cellulose ether is 100 or less, the viscosity efficiency is low, so there is a fear that the amount of use increases, and in the case of the cellulose ether of 20,000 or more, the production efficiency may decrease.

On the other hand, the present invention provides a water-soluble paint containing the thickener.

The content of the thickener is preferably 0.1 to 1.0% by weight relative to the total weight of the water-based paint composition, and when the thickener is used in an amount of less than 0.1% by weight, the thickening efficiency in paint, sag resistance and storage stability, etc. Improving the properties of the product may be inadequate, and when used in excess of 1% by weight, there may be a problem of workability due to high viscosity or an increase in cost due to an increase in input amount.

In addition to the thickener, general additives such as water, pigments and water-soluble emulsions, dispersants, anti-foaming agents and the like can be used in the water-based paint composition according to the present invention as is conventionally used in this field.

For example, water used in the water-based paint composition may be included within a range generally used in this field, and preferably 25 to 45% by weight of water based on the total weight of the paint composition may be used.

Further, a coloring pigment such as titanium dioxide may be used as the pigment, and may also include a body pigment such as aluminum silicate, calcium carbonate, talc or a combination thereof. Here, the pigment may be included within a range generally used in this field, and preferably is included within a range of 35 to 55% by weight based on the total weight of the paint composition.

As another component, a water-soluble emulsion, a vinyl acetate-based emulsion or an acrylic emulsion may be used.

The vinyl acetate-based emulsion or acrylic emulsion may be prepared by emulsion polymerization of a vinyl acetate-based monomer composition or an acrylic monomer composition in an aqueous medium (for example, water), respectively, in the presence of a polyvinyl alcohol-based material.

The polyvinyl alcohol-based material may include anionic-modified polyvinyl alcohol such as sulfonic acid-modified polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, or a combination thereof.

The vinyl acetate-based monomer composition may include a vinyl acetate-based monomer, and the acrylic monomer composition may include an acrylic monomer.

In addition, the vinyl acetate-based monomer composition and the acrylic monomer composition may further include other components, respectively.

The vinyl acetate-based monomer may include vinyl acetate, and the acrylic monomer may include ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, and butyl acrylate. , Butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, cyclohexyl acrylate, alkoxyethyl acrylate, or combinations thereof.

The other components include monomers that can be copolymerized with the vinyl acetate-based monomer and the acrylic monomer, respectively (eg, divinylbenzene, divinyl adipate, ethylene glycol di(meth)acrylate, diethylene glycol di(meta) )Acrylate); Water-soluble oligomers (eg, 2-methacrylamide-2-methylpropanesulfonic acid copolymer, sodium methacrylate-4-styrenesulfonate copolymer, polyvinylpyrrolidone, poly(meth)acrylate); Polymerization initiators (for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide); Polymerization regulators (eg, methanol, ethanol, propanol, acetone, dodecyl mercaptan); Emulsifiers (eg, sodium lauryl sulfate) and combinations thereof.

The water-soluble emulsion may be included within a range generally used in this field, and is preferably included within a range of 10 to 20% by weight based on the total weight of the paint composition.

The dispersing agent may include sodium citrate, calcium stearate, zinc stearate, distearyl dimethyl ammonium chloride, or a combination thereof.

The anti-foaming agent includes dimethyl polysiloxane, silicone, silica, sorbitan monostearate, silicone resin, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, mineral oil, oxyteraline, or combinations thereof. It may include.

The preservatives include methanethiol, ethanethiol, 1-propanthiol, 2-propanthiol, butanethiol, tert-butyl mercaptan, pentanethiol, coenzyme A, glutathione, cysteine, 2-mercaptoethanol, dithioerythritol, 2-mercaptoindole, transglutaminase, or combinations thereof.

The pH adjusting agent may include ammonia anhydride, ammonium phosphate, dimethyl ethanol amine, formic acid, sodium bicarbonate, sodium hydrogen carbonate, triethyl amine or a combination thereof.

In addition, additives common in this field may be used within the general range used in this field.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example One

Degree of substitution of hydroxyethyl group MS (average number of moles of hydroxyethyl groups bound per unit of cellulose) is 2.8, and degree of substitution of cetyl bromide group (-C ₁₆ H ₃₂ Br), which is a hydrophobic group (1 unit of cellulose) An aqueous paint composition was prepared by mixing the components shown in Table 2 below in a mixing ratio using hydroxyethyl cellulose ether (HMHEC) having a viscosity of 1,900 cps and an average weight percent of sugar-bonded hydrophobic groups) of 0.5 weight percent.

That is, acrylic emulsion resin, white pigment, extender pigment, and water are used as binders, and wetting agents, dispersants, anti-foaming agents, anti-freezing agents, PH regulators, preservatives, film-forming aids, and thickeners are added as additives to improve the properties of paints. A water-based paint coating was prepared. In Table 1 below, the unit of content of each component is% by weight.

Water-based paint composition Water paint composition ratio (% by weight) water 36 Wetting agent 0.2 Dispersant 0.4 Antifoam 0.2 Antifreeze 1.5 Titanium dioxide (white pigment) 15.1 Aluminum silicate (constitutional pigment) 7.1 Calcium carbonate (constitution pigment) 15.7 Talc (constitution pigment) 5.0 antiseptic 0.2 Styrene-acrylic emulsion 17.1 Coating forming aid 0.8 pH adjuster 0.2 HMHEC thickener 0.5 Sum 100

* Wetting agent: CF-10, a product name sold by DOW

* Dispersant: Product name 44S sold by Sanocof Co., Ltd.

* Antifoam: Product name SN-1300 sold by Sanocof Co., Ltd.

* Antifreeze: Ethylene glycol

* Colored pigment: titanium dioxide (TiO ₂ )

* Sieving pigment: aluminum silicate, calcium carbonate, talc

* Preservative: Troysan 174 sold by Troy chemical corp.

559)* Styrene-acrylic emulsion (Acronal sold by BASF

559)

* Film forming aid: Texanol™ sold by Eastman chemical company

* pH adjuster: AMP-95 sold by Eastman chemical company

Example 2 to 3 and Comparative example 1 to 4

A water-soluble paint composition was prepared in the same manner as in Example 1, except that the hydroxyethyl cellulose ether (HMHEC) substituted with the hydrophobic group had the hydrophobic group substitution degree and viscosity specified in Table 2 below.

CE type Viscosity (cps) Hydrophobic group substitution degree (% by weight) Example 1 High viscosity HMHEC 1,900 0.5 Example 2 High viscosity HMHEC 9,800 0.6 Example 3 High viscosity HMHEC 19,000 0.8 Comparative Example 1 HEC 2,000 - Comparative Example 2 HEC 4,000 - Comparative Example 3 Low viscosity HMHEC 500 0.4 Comparative Example 4 High viscosity HMHEC 28,900 1.3

CE: Cellulose ether

HMHEC: Hydroxyethyl cellulose substituted with a hydrophobic group (cetyl bromide)

HEC: hydroxyethyl cellulose

Viscosity: The viscosity of a 1% by weight aqueous solution measured at 25°C and 6 rpm with a Brookfield viscometer

Based on.

Evaluation example

The aqueous paint compositions prepared in the above Examples and Comparative Examples were evaluated for physical properties through the following physical property evaluation methods, and the results are shown in Table 3 below.

(1) Workability

Each water-based paint composition was applied on a slate base (by-wall slate) using an aqueous roller (a water-based roller of an artisan brush). During this coating operation, the degree of splashing of the water-based paint composition was observed with the naked eye to evaluate the workability as 4 grades as follows. It means that the workability is better as the water-based paint composition does not easily splash around.

◎: Excellent, ○: Good, △: Normal, ×: Inferior

(2) Thickening efficiency

The KU viscosity of the paint obtained by adding the same amount of the cellulose ether thickener was measured, and the higher the viscosity value, the better the viscosity efficiency.

(3) sag resistance

Each water-based paint composition was applied on a glass plate using an aqueous roller (a water-based roller of an artisan brush). When the glass plate coated with aqueous paint is scratched in the horizontal direction with a Sagmeter (Anti-SAG METER ASM-3 of Sheen Instruments Limited), the aqueous paint is removed according to the direction in which the Sagmeter has passed to form a lateral valley. Thereafter, the glass plate was placed vertically, and the degree of sagging resistance in the transverse direction was compared by evaluating the sag resistance as 4 grades as follows. It means that the sag resistance is inferior as the number of the missing portions is larger.

◎: Excellent, ○: Good, △: Normal, ×: Inferior

(4) Storage stability

After each aqueous paint composition was stored at room temperature for 1 month, the degree of segregation of the precipitate was visually observed to evaluate storage stability as 4 grades as follows. The smaller the degree of sedimentation, the better the storage stability.

◎: Excellent, ○: Good, △: Normal, ×: Inferior

(5) Color expression

Color expression is an experiment to compare the degree of color expressed according to the difference in thickener by adding the same amount of colored pigment after making white paint. After adding the colored pigment by weight and stirring uniformly, a 100-micron coating film is formed on a concealed paper using a film applicator. After the coating film was dried for 40 hours or more, a specimen was prepared, and the color difference compared to a standard using a colorimeter was evaluated as 4 grades as follows. The larger the color difference, the better the color expression.

◎: Excellent, ○: Good, △: Normal, ×: Inferior

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Workability ◎ ◎ ◎ × × ◎ × Thickening efficiency (KU) 101 111 127 95 98 95 131 Sag resistance △ ○ ◎ × △ × ◎ Storage stability ○ ◎ ◎ △ △ × ◎ Color expression ◎ ◎ ◎ ◎ ◎ ◎ △

Referring to Table 3, in the case of the water-based paint compositions of Examples 1 to 3 prepared according to the present invention, a comparison using a hydroxyethyl cellulose thickener containing no hydrophobic groups (cetyl bromide) or less than 0.5% by weight It can be seen that, compared to the water-based paint compositions prepared in Examples 1 to 3, the workability, sag resistance, and color expression are equal to or greater, while the thickening efficiency and storage stability are remarkably excellent. On the other hand, in Comparative Example 4 using a hydroxyethyl cellulose thickener containing a hydrophobic group of 1.3% by weight, it can be seen that the workability and color expression are poor.

As described above, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the protection scope of the present invention should be interpreted by the claims below and all technical spirits within an equivalent range Should be interpreted as being included in the scope of the present invention.

Claims (8)

Contains a cellulose ether substituted with a hydrophobic group,
At least one hydrogen of the hydrophobic group is substituted with one or more halogen groups selected from the group consisting of fluorine, chlorine, bromine and iodine, and the remaining hydrophobic groups are hydrocarbon groups having 4 to 20 carbon atoms (C ₄ to C ₂₀ ),
The degree of substitution of the hydrophobic group is 0.6% by weight to 0.8% by weight,
The cellulose ether has a viscosity of 8000cps to 20000cps based on a 1% by weight aqueous solution measured at 25°C and 6rpm with a Brookfield viscometer. delete According to claim 1,
The cellulose ether is an aqueous paint thickener, characterized in that at least one selected from the group consisting of alkyl cellulose, hydroxyalkyl cellulose and hydroxyalkyl alkyl cellulose. According to claim 1,
The cellulose ether is a hydroxyethyl cellulose thickener for aqueous paint, characterized in that. According to claim 1,
The cellulose ether is a hydroxyethyl group substitution degree (MS) is a hydroxyethyl cellulose thickener for aqueous paint, characterized in that 0.8 to 4.5. delete A water-based paint composition comprising the thickener for water-based paint according to any one of claims 1 and 3 to 5. The method of claim 7,
The content of the thickener is water-based paint composition, characterized in that 0.1 to 1.0% by weight relative to the total weight of the water-based paint composition.